Health

Mapping Your Genes

At-home genetic testing may help reveal what diseases you're at risk for developing.

Mapping Your Genes
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THE PIONEERS IN GENE DECODING
These four companies are leading the way in genetic testing but the field is growing quickly.

Decodeme
decodeme.com
Cost: $985
Service: Decodeme assesses your genetic risk for 29 diseases and traits, including lactose intolerance and brain aneurysm. It offers you the chance to trace ancestry and compare genetic information with friends and family.

DNA Direct
dnadirect.com
Cost: Varies by test from $175 for responsiveness to the blood thinner Warfarin to $3,456 for comprehensive testing for genes associated with breast and ovarian cancer
Service: DNA Direct offers testing for specific health conditions, including breast cancer, blood clotting disorders, and cystic fibrosis, based on family history. It also checks for genetic traits that can affect treatment for particular diseases, such as cancer and heart disease. The company offers preand post-testing counseling services.

Navigenics
navigenics.com
Cost: $2,500 for the initial report and first year of membership, $250 a year for continuing membership
Service: Navigenics looks for markers that have been associated with 22 common conditions that are "actionable," that is, you can do something to prevent or detect them early. The company offers telephone counseling with genetic counselors.

23andme
23andme.com
Cost: $399
Service: 23andme offers a range of personalized genetic information from markers for medical conditions, such as breast cancer, heart disease, and lupus, to other traits such as bitter taste perception, alcohol sensitivity, and earwax type (there are two types: wet is dominant and dry is recessive). Like Decodeme, the service also allows you to compare genes with friends and family and trace your ancestry to Europe, Asia, and Africa.

GENETICS BASICS

Every cell in your body contains DNA, a long molecule that carries the instruction manual (written in 23 pairs of chromosomes) for making you. You have two copies of each chromosome, one from your father and one from your mother. They are written in a code of bases, commonly abbreviated as A, T, C, and G.
On each chromosome are thousands of genes. Variations in your genetic code give you red hair or blue eyes. But single-letter differences in the genetic code (e.g., a G instead of a C) in your DNA can also give you mutations that can predispose you to disease.

Most diseases develop from a mix of genetic and environmental factors, often involving multiple errant genes. Over the past decade, scientists have identified places in the chromosomes where there are differences in the genetic code that can be used as markers (called SNPs, pronounced "snips," short for single nucleotide polymorphisms). Researchers have found that people with certain markers are at greater or lesser risk of developing particular diseases.

Genetic testing companies have developed ways to scan DNA to look for these markers. So if you have some of the markers associated with type 2 diabetes, for example, you may be at increased risk of developing the disease. The companies don't predict you're going to get diabetes. Rather, they tell you the average person's risk of developing the disease and how your risk compares.

Are we ready for genetic testing?
The idea of plumbing the depths of your genetic code may sound tantalizing. But some critics say overzealous entrepreneurs are leaping ahead of the science. "In the last few years there have been many gene discoveries, but to act on the science is premature," says Muin J. Khoury, M.D., Ph.D., director of the National Office of Public Health Genomics. "For the most part, we don't know how to interpret the findings from the research." And some experts question whether the information is ready to be used by consumers. "These companies have not met the standards of a clinical genetics lab in a healthcare setting," says Michael S. Watson, Ph.D., executive director of the American College of Medical Genetics.

Watch for new regulations
State and federal health officials are concerned enough about potential abuses to begin investigating the industry. In June, the California Department of Public Health sent "cease and desist" letters to 13 genetic testing companies, demanding they prove they're in compliance with state and federal laws governing medical procedures. (Some companies are offering tests direct to consumers without an order from a physician.) The American College of Medical Genetics and an advisory committee to the U.S. Department of Health and Human Services are calling for more regulation.

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